Computers generally have the capability to receive input data representing numerical entries and the location of a cursor or other graphical objects on a graphical display. Graphical location data is conventionally entered into a computer using a mouse detached from a keyboard or, where space is limited as it is with portable "laptop" or "notebook" computers, by using four cursor arrow keys or a trackball built into the keyboard. Numerical data, on the other hand, is conventionally entered into a computer utilizing an array of ten keys arranged either in a single row across the top of a keyboard, or in four rows as a numerical keypad detached from, or at one end of, a keyboard. Such a numerical keypad is not often used with portable computers because of space limitations.
A mouse is generally preferred over cursor keys and even a trackball because a mouse facilitates simpler, faster, and more precise entry of graphical location data into a computer. A mouse is therefore commonly connected to a input/output (I/O) port of a portable computer to supplement cursor keys and, if one is provided, a trackball. However, portable computers generally have a limited number of I/O ports and when a mouse is connected to an I/O port, there is often not another port available for a device such as a numerical keypad. For this reason, and the additional important reason that users of portable computers are generally interested in conserving space, numerical keypads are not often used with portable computers. Nevertheless, a numerical keypad would simplify the entry of numerical data and also reduce the time required to make such entries.
For the foregoing reasons, there is a need to be able to input to a portable computer both graphical location data as well as numerical data via a single port of a portable computer without using a large amount of space.